Proper preparation is key for success when giving any sort of oral presentation. This is true for people who stutter and for people who are fluent. If anyone, pws or not, tells you otherwise they are lying to you. Repeating what the others with advice said: write/type the speech out (proof read it, first) and practice practice practice. You said you have a few weeks before the assignment is due so start practicing now. Verbally repeat and repeat your speech until it's basically memorized. When doing this pay attention to your breath, mouth, and throat noticing any tightness or blockages and how to work through them.